The game starts at 0:00.

When you're stuck at base for the first few seconds, you need to be buying your items, deciding if you want to invade, and maybe discussing enemy summoner spells or counterplay if someone is running a strange gimmick like 2 offensive spells or ignite bot lane. When you're released, you should be grouping with the team and either invading or body warding to prevent successful invasions. Every time I've been on the giving or receiving end of a successful gank, it's because either their mid laner is sitting under mid turret doing nothing, or someone hasn't even started buying their items. When you body ward (or just straight up ward) the choke points all you have to do is flash through a wall and you deny them first blood.

I'm really tired of people who think they can just waltz into lane at 2:30 or later. Junglers get an awful leash if one of the bot laners is missing and no leash at all if top is missing and they start there. If the jungler is missing they also get no leash and lose early pressure. If a mid/top misses even 1 minion worth of experience it can mean a lost lane because of the snowbally aggressive nature of mid lane.

Don't tab out if you can't return as soon as the game starts, and don't play if you can't connect.